Lens for vault-lights



(No Model.)

J. DALY.

. LENS FOR VAULT LIGHTS. No. 274,086. Patented Mar. 13,1883.

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UNITED STATES PATENT OFFICE.

MICHAEL J. DALY, OF NEIV YORK, N. Y., ASSIGNOR TO JAMES GREY PEN-NYCUICK, OF BOSTON, MASSACHUSETTS.

LENS FOR VAULT-LIGHTS.

SPECIFICATION forming part of Letters Patent No. 274,086, dated March13, 1883.

Application filed October 5, 1882. (No model.)

To all whom it may concern:

Be it known that 1. MICHAEL J. DALY, a citizen of the United States, andresiding at New York, in the State of New York, have inq vented a newand useful Improvement in Lenses A k for Vault-Lights, of which thefollowing is a specification.

My invention relates to the lenses used in iron frames for illuminatingpurposes, of which the following is a specification.

Heretofore lenses of a form projecting under the plate or tile in whichthey are set have been either of a prismatic form or half-round, oneside or the back with a plain surface at an angle with the horizontal ofthe head, and the opposite or refracting surface or face at right angle,or nearly so, with the head, and of rounded or convex form. This latterI find absorbs a great portion of the light, and prevents the naturallysilvering action of light on the back or reflecting plain, and alsolimits the light from the lens to the condition of the weather.

The object of my invention consists in making the tongue or projectingportion of the lens of a perfectly semi-prismatic form, set on a headwith the reflecting surface or back at an angle of about forty-five (45)degrees with the horizontal of the head, and the front or refractingportion of the tongue at a corresponding angle, or nearly so. By thisarrangement I obtain a natural silvered reflecting-lens under anycondition of the weather, and which is fully more efiective in dull thanin bright weather.

In the accompanying drawings, Figure Iis a side elevation; Fig. II, afront view of the same; Fig. III, a section at line 00 m, Fig. I.

Fig. IV is a. side elevation of a modification of my improved lens; Fig.V, a front view of the same; and Fig. VI, a section at-line zz, Fig. IV.Similar letters represent similar parts in all the figures.

A is the top or head of the lens, made in any desired shape or form tofit the frame or tile which is to receive the same.

B is the downward-projecting portion of the lens, set at an angle ofabout forty-five degrees to the surface of the head A. This portion ofthelens, is of a form of atrihedral prism, one of the sides a formingtheback of the lens, and the inclined sides I) b forming the front part ofthe same, or the reflecting-surfaces. The end 0 of the lens is cut offperpendicular or square to the head A, or nearly so.

In Figs. IV, V, and VI, which are only modifications of the above, theouter edge of the two side surfaces, b b, is cut square or parallel withthe back a, or refiectiugsurface, forming a plain straight surface, (I,at the front, in combination with the side surfaces, b b.

The downward-projectingpart B of the lens should be ofalengthconsiderably greater than the greatest depthof the prism.

The construction of alens gives an area of the reflecting-surface manytimes greater than the area of the opening which admits the light,

and by placing the prism at an acute angle of about forty-five degrees(45) with the horizontal surface of the head A a greatly increased areaof reflecting-surface is obtained, as well as of the diffusing-surfaces.

What I claim as my invention, and desire to secure by Letters Patent, is

An illuminating-lens consisting of the combination ofaprojectingtrihedral prism, B, with a head or bulls-eye, A, at an angleof about forty-five degrees, substantially in the manner and for thepurpose set forth.

MICHAEL J. DALY.

Witnesses HENRY E. RoEDEE, WALTER J. KELLEY, J. B. NoNEs.

